3114 BC: According to the most widely accepted correlations between the Western calendar and the calendar systems of pre-ColumbianMesoamerica, the mythical starting point of the Mesoamerican Long Count calendar cycle occurs in this year.[4] The Long Count calendar, used and refined most notably by the Maya civilization but also attested in some other (earlier) Mesoamerican cultures, consisted of a series of interlocked cycles or periods of day-counts, which mapped out a linear sequence of days from a notional starting point. The system originated sometime in the Mid- to Late Preclassic period of Mesoamerican chronology, during the latter half of the 1st millennium BC.[5] The starting point of the most commonly used highest-order cycle[6]—the b'ak'tun-cycle consisting of thirteen b'ak'tuns of 144,000 days each—was projected back to an earlier, mythical date. This date is equivalent to 11 August 3114 BC in the proleptic Gregorian calendar (or 6 September in the proleptic Julian calendar), using the correlation known as the "Goodman-Martínez-Thompson (GMT) correlation". The GMT-correlation is worked out with the Long Count starting date equivalent to the Julian Day Number (JDN) equal to 584283, and is accepted by most Mayanist scholars as providing the best fit with the ethnohistorical data.[7] Two succeeding dates, the 12th and 13 August (Gregorian) have also been supported, with the 13th (JDN = 584285, the "astronomical" or "Lounsbury" correlation) attracting significant support as according better with astronomical observational data.[8] Although it is still contended which of these three dates forms the actual starting base of the Long Count, the correlation to one of this triad of dates is definitively accepted by almost all contemporary Mayanists. All other earlier or later correlation proposals are now discounted.[7] The end of the thirteenth baktun was either on December 21 or 23 of 2012 (supposed end of the world).

^Most commonly used in the Classic period Maya inscriptions; some other Maya calendar inscriptions of this period note even longer cycles, while later Postclassic-era inscriptions in Maya cities of northern Yucatán generally used an abbreviated form known as the Short Count. See Miller and Taube (1993, p.50); Voss (2006, p.138).

^After a modified proposal championed by Floyd Lounsbury; sources that have used this 584285 correlation include Houston (1989, p.51), and in particular Schele and Freidel (1990, pp.430 et seq.). See also commentary by Finley (2002), who although making an assessment that the "[584285 correlation] is now more popular with Mayanists", expresses a personal preference for the 584283 correlation.